In recent years, a secondary battery, which can be charged and discharged, has been widely used as an energy source for wireless mobile devices. In addition, the secondary battery has attracted considerable attention as a power source for electric vehicles (EV), hybrid electric vehicles (HEV), and plug-in hybrid electric vehicles (Plug-in HEV), which have been developed to solve problems, such as air pollution, caused by existing gasoline and diesel vehicles using fossil fuels.
Small-sized mobile devices use one or several battery cells for each device. On the other hand, middle or large-sized devices, such as vehicles, use a battery module having a plurality of battery cells electrically connected to each other because high output and large capacity are necessary for the middle or large-sized devices.
Preferably, the battery module is manufactured so as to have as small a size and weight as possible. For this reason, a prismatic battery or a pouch-shaped battery, which can be stacked with high integration and has a small weight to capacity ratio, is usually used as a battery cell (a unit cell) of the battery module. In particular, much interest is currently focused on the pouch-shaped battery, which uses an aluminum laminate sheet as a sheathing member, because the pouch-shaped battery is lightweight, the manufacturing cost of the pouch-shaped battery is low, and it is easy to modify the shape of the pouch-shaped battery.
Battery cells constituting such a battery module are secondary batteries which can be charged and discharged. Consequently, a large amount of heat is generated from the high-output, large-capacity secondary batteries during the charge and discharge of the secondary batteries. In particular, the laminate sheet of each pouch-shaped battery widely used in the battery module has a polymer material exhibiting low thermal conductivity coated on the surface thereof with the result that it is difficult to effectively lower the overall temperature of the battery cells.
If the heat, generated from the battery module during the charge and discharge of the battery module, is not effectively removed from the battery module, the heat accumulates in the battery module with the result that deterioration of the battery module is accelerated. According to circumstances, the battery module may catch fire or explode. For this reason, a high-output, large-capacity battery module needs a mean for measuring and controlling the temperatures of battery cells mounted in the battery module.
To this end, a temperature sensor is connected to the battery cells for monitoring and controlling the operations of the battery cells in real time or at predetermined intervals. However, installation or connection of such a detection means very complicates a process of assembling the battery module, and a short circuit may occur due to wiring for installation or connection of the detection means.
For example, in a conventional battery module, a temperature sensor is located between the battery cells to measure the temperatures of the battery cells and thus the temperature in the battery module. The battery module is configured to have a structure in which the temperature sensor directly contacts the surface of each of the battery cells in order to more accurately measure the temperatures of the battery cells.
However, several problems occur when the temperature sensor is mounted in the battery module. For example, it is difficult and troublesome to insert the temperature sensor between the battery cells due to the internal structure of the battery module, which is very complicated due to a plurality of components constituting the battery module.
In addition, the surfaces of the battery cells are scratched when the temperature sensor is inserted between the battery cells. In this case, the battery module may malfunction, a short circuit may occur in the battery module, or the lifespan of the battery cells is reduced.
Consequently, there is a high necessity for a battery module that is capable of solving the above problems.